Operators & Service

Manual

DN320

EVI PRO AUDIO GROUP

Tel: (01562)741515 Fax: (01562)745371

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DECLARATION OF CONFORMITY

The Directive Covered by this Declaration

Equipment Type Product Name

The Basis on which Conformity is being Declared

The Products named above comply with the requirements of the above EU directives by meeting
the following standards:

EN 50081-1 (EN55022 class B)

Signed: .................................... N. G. Tembe

Attention!

The attention of the specifier, purchaser, installer, or user is drawn to special limitations to use
which must be observed when these products are taken into service to maintain compliance with
the above directives. Details of these special measures and limitations to use are available on
request, and are also contained in product manuals.

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Attention!

Cables:
This product should only be used with high quality, screened twisted pair audio cables, terminated
with metal bodied 3-pin XLR connectors. The cable should be connected to pin 1. Any other cable
type or configuration for the audio signals may result in degraded performance due to electromagnetic
interference.

Electric Fields:
Should this product be used in an electromagnetic field that is amplitude modulated by an audio
frequency signal (20Hz to 20KHz), the signal to noise ratio may be degraded. Degradation of up to
60dB at a frequency corresponding to the modulation signal may be experienced under extreme
conditions (3V/m, 90% modulation).

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CONTENTS

INTRODUCTION 8

THE DN320 PRESET EQUALISER 9

INSTALLATION 11

INSTRUMENT FAMILIARISATION 13

AUDIO CONNECTIONS 14

SPECIFICATIONS 15

SERVICE INFORMATION 16

SCHEMATICS

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THANK YOU FOR USING THIS KLARK TEKNIK PRODUCT

To obtain maximum performance from this precision electronic product, please study these instructions
carefully. Installing and operating the equaliser is not complicated, but the flexibility provided by its
operating features merits familiarisation with its controls and connections. This unit has been prepared
to comply with the power supply requirements that exist in your location.

Precautions

Before connecting this unit to the mains power, ensure that the operating voltage is correct for your local
supply.

Do not install this unit in a location subjected to excessive heat, dust or mechanical vibrations.

Safety Warning

This unit is fitted with 3-pin power socket: For safety reasons the earth lead should not be disconnected.

To prevent shock or fire hazard, do not expose the unit to rain or moisture.

To avoid electrical shock do not remove covers. Refer servicing to qualified personnel only.

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After you have unpacked the unit

Save all the packing materials - they will prove valuable should it become necessary to transport of ship
this product.

Please inspect this unit carefully for any signs of damage incurred during transportation. It has undergone
stringent quality control inspection and tests prior to packing and left the factory in perfect operating and
mechanical condition.

If, however, the unit shows a sign of damage, notify the transportation company without delay. Only
you, the consignee, may institute a claim against the carrier for damage during transportation.

If necessary, contact your supplier or as a last resort, your Klark Teknik importing agent, who will fully
co-operate under such circumstances.

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Introduction

The equaliser is a vital component in any audio system. The entire signal passes through it and so any
limitations imposed by the equaliser will compromise the performance of the whole system. For
example, an indifferently designed equaliser may introduce severe phase distortion, noise and other
anomolies related to centre-frequency accuracy, filter shape and attenuation accuracy which may
manifest themselves as an overall deterioration in the perceived sound quality of the system. Clearly this
in an unacceptable state of affairs, but fortunately your choice to utilise Klark Teknik equaliser product
will eliminate these problems, offering you unprecedented product performance coupled with the
highest filter calibration and reliability standards in the industry.

For many years Klark Teknik has been at the forefront of equaliser design, and have carried out detailed
research into optimum filter response characteristics, including their sonic performance.

The Series 300 range of equalisers is a direct result of this research. It should be noted that equalisation
cannot always overcome all frequency response related problems. There are applications where the
ability to cut or boost the response at a particular frequency, or over a certain bandwidth other than the
equaliser specified one, is required to overcome exceptionally difficult response anomalies or narrow
band feedback problems. When such an instance is encountered, it may be more appropriate to use
the greater range of control provided by a parametric type equaliser, where the centre frequency,
bandwidth and amplitude are all controllable.

When using an equaliser remember that the need to use large amounts of boost or cut within the
equalisation curve indicates that there may be something fundamentally wrong with the sound system
or room acoustics, which should be further investigated and corrected before final equalisation is
applied.

Both the input and output circuitry is electronically balanced. The input is voltage and current matched
and gives exceptional noise, distortion and CMR performance, while the output circuitry is based on
the Midas XL3 output stage giving high drive capability.

Operation is normally from the mains supply with the 24V DC supply being utilised upon the failure of
the mains. If no 24V is available then the internal relays will bypass the unit in the event of power failure.

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DN320 Equaliser

The Klark Teknik DN320 is a dual channel, 16 band equaliser offering 12dB of cut or boost in 2/3
octave steps between the frequencies of 20Hz and 20kHz.

Filter Shape and Combining Action

At the heart of any equaliser is the bank of filters used to shape the signal response, and Klark Teknik
utilise a proprietary filter circuit which replaces which replaces the conventional inductor based circuit,
at the same time, offering several performance advantages. Inductor based circuits are heavy, expensive
to produce and suffer from low frequency distortion and induced hum. Klark Teknik’s proprietary filters
on the contrary suffer none of these problems, yet offer unequalled phase response and control accuracy
with the additional benefits of low noise and minimal ripple.

The nature, shape and way in which individual equaliser filters combine, has a profound effect on the
control provided by the equaliser and on the resulting quality of sound. The majority of applications
within the sound reinforcement, broadcast and recording fields, require a smooth and continuous
equalisation response curve in order to correctly contour the overall response characteristics of a sound
system, loudspeaker, recording effect or audio channel. To achieve this, the individual filters must be
capable of combining smoothly together to result in a continuous response curve, free from shape
discontinuities in order to avoid unwanted audible peaks of anomalies in the final sound.

Individual channel level controls, overload indicators and bypass switches with incorporated low cut
filters are featured on the control panel.

Other features

The bypass switch silently removes the graphic equaliser sections from the signal path. Incorporated
in the bypass switch is a subsonic 18dB/octave roll-off filter (-3dB @ 30Hz).

Other features include an overload LED per channel, which warns of impending overload at any point
in the equaliser. A detachable security cover is an inherent feature to prevent unauthorised personnel
from tampering with the control settings.

This product is built to the same high electrical and mechanical standards as all Klark Teknik equipment
and is both robust and stylish. It occupies a standard one unit of rack space and has electronically
balanced inputs and outputs.

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Reliability Control

Even with the advanced technology incorporated in this product, each instrument is given the full backing
of Klark Teknik’s “reliability control” which proves each product against a specification consistent with
the highest professional standards. Only top quality components are used, and every unit is bench tested
and aligned before a burn-in period and final performance test.

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INSTALLATION

The DN320 is designed for fixed installations where it is conventionally mounted into a standard 19”
equipment rack. The unit occupies only 1U of height and due to the low operating power requirements
of this unit, heat generation is kept to a minimum allowing units to be stacked above each other with no
ill effects. For continued reliability it is not recommended that the equalisers are located immediately
above heat generating units such as power amplifiers or mixer power supplies. If this is unavoidable a
vent panel between the units is advisable.

Precautions

Do not install this unit in a location subjected to excessive heat, dust or mechanical vibration. before
connecting the unit to the mains supply, ensure that the operating voltage is correct for your local supply.
It is important that you observe the following precautions.

Voltage Selection & Power Connection

Connection to the mains supply is by means of a standard IEC power socket. The rear panel voltage
label indicates the voltage required for satisfactory operation of the unit. To change the mains voltage
please refer to the ‘ Voltage Changeover‘ section on page 12.

IMPORTANT Mains voltage adjustments should only be carried out by a qualified service technician.

The DC supply can be connected either by separate 4mm ( Banana ) plugs or by use of the dual stacking
version. Correct polarity must be observed for operation, though the unit is protected against reverse
polarity. Please refer to the section below regarding DC operation.

NOTE: As there is no power on/off switch on this unit, as soon as the power (Mains or DC ) is connected
the unit will be active.

Safety Warning

This unit is fitted with a 3-pin power socket. For safety reasons the earth lead MUST NOT be
disconnected. An internal ‘floating’ audio ground reference is used to ensure no earth loop problems
occur related to the installation of this unit. Should any ground loop problems be encountered they will
be caused by the commoning of the grounds of the other equipment connected to the equaliser.

The DN320 can be made the central ground reference as detailed on page12, this modification should
only be carried out by qualified service technician.

To prevent shock or fire hazard, do not expose the unit to rain or moisture, only replace fuses with the
correct type and rating.
Do not remove the covers, refer servicing to qualified personnel only.

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Audio Connections

The inputs and outputs are fully balanced on XLR connectors and are wired conventionally with pin
1 as ground. Because the system is fully floating, either pin 2 or pin 3 can be designated as hot (
phase ) so long as the same protocol is adhered to for both inputs and outputs. To comply with
EMC regulations filtering is incorporated into this unit. To maximise the benefits of this it is recom-
mended that the XLR shell is not connected to the audio ground.

DC Operation

This unit is designed primarily for operation from the mains supply. The DC connection is intended
for use as a backup power for evacuation and similar uses in conditions of mains failure. Upon
failure of the mains supply, as the unit is already operational the DC supply is only required to
furnish the current necessary to maintain operation, nominally 200mA at 24V.

If it is required to power the unit only from the DC supply, this is quite acceptable but the power
supply MUST be capable of providing an initial 1.5A start up current to initiate the switched mode
power supply. The duration of this current draw is only for approximately 5 milliseconds after which
the current drops to 200mA. This is no problem when running from batteries but could overload a
bench power supply. Please refer to the application note later in the manual for a method of starting
and running from a supply that only gives 250-300mA .

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Front Panel Functions

Other than the power on and clip indicators no user controls or indicators are available with all set-
up controls secured behind the central removable panel.
Remove the three pozidrive screws to gain access to these controls.

The unit has two identical channels A & B, each channel is fitted with:-

1. Input level control allowing system gain of up to +12dB in the fully clockwise position
and attenuation of up to -6dB in the fully anticlockwise position. When the ‘slot’ is horizontal
it is in the 0dB, unity gain position.

2. EQ & subsonic filter in/out switch. This switch has three positions and allows the 30Hz
subsonic filter to be connected in or out of circuit as well as bypassing of the equaliser. These
are selected as follows:
Down: Equaliser only in circuit.
Centre: Equaliser & subsonic filter are both out of circuit, the
gain control is still active.
Up: Both the equaliser & the subsonic filter are in circuit.

3. Sixteen high quality, sealed rotary preset filter level controls each providing between +12dB
boost and -12dB cut at the 2/3 Octave ISO standard frequencies. When the ‘slot‘ is hori
zontal the filter is flat.

4. Channel overload led. The signal level is monitored at several separate points within the
circuitry of the unit. If any one of these signals exceeds a threshold set 3dB below clipping the
led will light. It must be remembered that excessive boost at some frequencies combined
with a high average input signal can occasionally cause the clip sensing threshold to be ex
ceeded. In this event the gain control should be turned down to correct the problem.
However, if the input signal itself exceeded 20 dB the input stage will be overloaded. If this
problem arises then the signal level from the equipment feeding the equaliser must be re
duced.

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Rear Panel Functions

5. Mains is supplied via an IEC standard 3 pin connector. A compatible power cord is supplied
with the unit.

6. The mains fuse is located in the draw that is part of the mains input connector. A spare fuse is
also stored here. Disconnect the unit from the mains supply before replacing the fuse. Always
replace the fuse with the correct type and rating.

7. Two sockets are provided for the connection of the 24V DC supply. These are standard
4mm ‘banana’ type. The sockets are on a standard 19mm pitch to allow the use of twin
stackable connectors. The polarity of the DC supply must be maintained for operation though
incorrect connection will not damage the unit.

8. Input and output connections are via complementary XLR style connectors. For wiring
details see the page entitled Audio Connections.

NOTE: The security cover is normally fixed with M3 pozidrive screws. For installations where
the utmost security is required these can be replaced with tamperproof type of M3 x 6mm.

Audio Connections

Inputs

The input circuitry is a transformerless, electronically balanced design which achieves a symmetry of
better than -50dB from 20Hz to 10kHz.

It is always preferable to drive the equaliser from a balanced source. If only an unbalanced source
is available it is recommended that it is connected as shown below. Connect the screen only at the
equaliser end.

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Outputs

The standard outputs are electronically balanced and is capable of driving

It is recommended that the equaliser feeds into a balanced input, however to feed an unbalanced
input it is necessary to connect the antiphase output to ground. This is best carried out on the XLR
output connector of the equaliser.

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Technical Specifications

Inputs Two
Type Electronically balanced
Impedance
Balanced 20Kohms
Unbalanced 10Kohms
Max input level 20dBm
Outputs Two
Type Electronically balanced
Source impedance 50 ohms
Min.load impedance 600 ohms
Max.level 20dBu with 2Kohm load
Performance
Frequency response
20Hz to 20kHz, EQ flat +/-0.5dB
THD+N @ +4dB <0.01% @ 1kHz
Equivalent input noise
(20Hz to 20kHz unweighted) <-88dBu
Gain -6 to +12dB
Filters
Type Proprietary “combining”
ISO centre frequencies 16, 20Hz to 20kHz
Frequency tolerance 5%
Maximum boost/cut +/-12dB
Subsonic filter 18dB/octave, -3dB @ 30Hz
Power requirements
AC Voltage 115/230 +/-12%, 50/60Hz
Consumption <15VA
DC Voltage 24V +/-12%
DC Consumption <250mA
Weight
Nett 2.5kg
Shipping 4kg
Dimensions
Width 482mm (19 inches)
Height 45mm (1 3/4 inches)
Depth 210mm (8 1/4 inches)
Terminations
Inputs 3 pin XLR
Outputs 3 pin XLR
AC power 3 pin IEC
DC power 2x4mm “Banana” type

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THE FOLLOWING INFORMATION IS FOR THE USE OF QUALIFIED SERVICE
PERSONNEL ONLY

Do not attempt any of the following adjustments yourself

The following adjustments require the removal of the cover. Proceed as follows:-

1. Disconnect the unit from the mains and DC supply.

2. Remove the eight pozidrive cover screws, 3 on the top, 2 on each side and 1 on the rear.
Keep these safe for reuse later. Lift off the cover.

Voltage Changeover

The unit is normally shipped preset to the mains supply voltage required for the country. This is indicated
on the rear panel.

To select the alternative voltage it is only necessary to slide the voltage selector switch, located to the
right of the mains transformer, to the other position.

Please ensure that the rear panel voltage label is removed and replaced with one stating the new voltage
setting.

Making the DN320 the system ground reference

Under certain unusual operating environments it may be necessary to use the equaliser as the main
ground reference and tie other signal grounds to it. This is easily accomplished as follows:-

1. Remove the M3 pozidrive screw located in the centre of the board labelled ‘ST3.’ &
‘Ground Link’.

2. Fit a solder tag onto the screw and refit ensuring the tag is located over the bare pcb section
to the left of the screw.

3. Solder the tag to the circuit board.

4. Replace the cover after adjustment.

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KLARK TEKNIK Application Note 1

A Method of Starting & Powering the

CAUTION. The following is given as guidance only and should only be carried out by suitably
qualified and experienced personnel.
The information is given in good faith and is not intended as a definitive method of
achieving the desired results.

Problem: “I only have a 250-300mA 24V power supply. How can I run the DN320 from it?”

Answer: 1. With the supply OFF, connect a capacitor of approximately 10000 mfd and a
working voltage of at least 25V across the output terminals.
2. Connect the power supply to the DN320 via a suitable switch, leave in the open
position.
3. Turn on the power supply and allow a couple of seconds for the capacitor to charge.
4. Close the switch and the DN320 will power up.

It does this because the capacitor provides sufficient energy to provide the switch mode supply’s start
up current. Once the supply is running only the nominal 200mA operating current is required.

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